Description
Ipamorelin (development code NNC 26-0161) is a synthetic pentapeptide belonging to the growth hormone secretagogue (GHS) class. Its amino acid sequence — Aib-His-D-2-Nal-D-Phe-Lys-NH₂ — was derived from growth hormone-releasing peptide-1 (GHRP-1) and incorporates several non-natural residues that confer receptor selectivity [5]. The compound acts as a selective agonist at the ghrelin/GHS receptor (GHS-R), a property that has made it a widely referenced tool in preclinical endocrinology research [3].
A defining structural feature studied in early pharmacological work is ipamorelin's high selectivity for GH release relative to other pituitary hormones. In preclinical models, ipamorelin stimulated GH secretion from rat pituitary cells with potency comparable to GHRP-6, yet — unlike GHRP-2 and GHRP-6 — did not produce statistically significant elevations in ACTH or cortisol even at doses more than 200-fold above the GH-release ED₅₀ [3]. This selectivity profile has positioned ipamorelin as a useful reference compound for researchers investigating GHS-R–mediated signaling pathways.
In the broader peptide research landscape, ipamorelin is studied alongside other growth hormone secretagogues to probe IGF-1 signaling and satellite cell biology [2]. Published preclinical work has also examined its combination with the GHRH analog CJC-1295 in murine models of glucocorticoid-induced muscle loss, where the pairing was reported to influence maximum tetanic tension [1]. These experimental contexts reflect its primary utility as an investigative tool for understanding GHS-R pharmacology and downstream anabolic signaling in controlled laboratory settings.
Researchers seeking to characterize receptor kinetics, downstream pathway behavior, or peptide–receptor interactions in vitro frequently include ipamorelin as a comparator or primary compound, given the extensive mechanistic literature describing its selectivity and potency characteristics [3][4].
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References
[1] Injectable Peptide Therapy: A Primer for Orthopaedic and Sports Medicine Physicians. The American Journal of Sports Medicine, 2026. https://pubmed.ncbi.nlm.nih.gov/41476424/
[2] Therapeutic Peptides in Orthopaedics: Applications, Challenges, and Future Directions. Journal of the American Academy of Orthopaedic Surgeons. Global Research & Reviews, 2026. https://pubmed.ncbi.nlm.nih.gov/41490200/
[3] Ipamorelin, the first selective growth hormone secretagogue. European Journal of Endocrinology, 1998. https://pubmed.ncbi.nlm.nih.gov/9849822/
[4] Safety and Efficacy of Approved and Unapproved Peptide Therapies for Musculoskeletal Injuries and Athletic Performance. Sports Medicine (Auckland, N.Z.), 2026. https://pubmed.ncbi.nlm.nih.gov/41966639/
[5] Ipamorelin. Wikipedia. https://en.wikipedia.org/wiki/Ipamorelin
